... (mm) 3.Welding range:400~4500(mm) Four-head window welding machine is one of the ... necessary equipments processing PVC win-door, it can achieve the whole welding process independently. It ... used for PVC door-window welding.2.Welding four, three,two or one corner, transom,cross ... transom and special angles.3.Four-heads can work simultaneously, individually or in combination.4. ...